Battery backup power for NW PA

New to this site and new to back up power requirements. I am in NW PA and we have occasional electrical outages. They last between 1 and 6 hours. I have a gas well which saves us quite a bit but when the power is interrupted I need an alternative source to power the ignition for the furnace and fan to force the warm air into the house. I also need to power the pump for the well and supply some lights as well as ignition for the range and hot water heaters . Not a whole lot of demand but essential in 20 degree weather. My question is what kind of battery power do I need and how does one install a sub panel to take over when the grid fails. I think a small generator would recharge my system. I would look to have two banks for supply to alternate for charging in case its a prolonged outage.
Than you

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,188 admin
    Re: Battery backup power for NW PA

    David,

    I am moving this to its own thread--It should make it less confusing for everyone if all of your discussions are in one place.

    We really need to now your daily (or 6 hour loads) both in kWH hours (watts*hours) and peak load...

    To give you an idea of a really nice setup... You could use an XW 4548 Hybrid inverter + a minimum size battery bank. Add a genset for longer outages and you are ready to go...

    Not knowing your loads, but working out a minimum sized system:
    • XW 4.5 kW inverter with 120/240 VAC split phase support
    • XW includes a 240 VAC battery charger
    • XW available option automatic generator control
    • 450 - 600 AH battery bank Assume minimum state of charge 20% (usually 50% recommended, but for emergency use--using 80% of the charge a few times a year is not the end of the world
    • Battery Bank can be flooded cell or AGM. Flooded cell usually cheaper, more rugged, longer life. AGM is an ideal lead acid battery--very efficient and clean, good life, weakness is overcharging (good charger plus remote battery temperature sensor should address that issu).
    So--assume 600 AH x 48 volt battery bank, assume using 80% of battery capacity, 85% efficient inverter, and a 10 hour backup support time:
    • 600 AH * 48 volts * 0.85 * 1/10 hours * 0.8 battery use = 1,958 watts maximum load for 10 hours
    That sort of sets the upper limit--if you take a minimum system design (using this fairly large inverter/charger with a minimum capacity battery bank, and use the bank aggressively)--You can average 1,900 watts (or a bit less) average load for 10 hours.

    Or a lighter load for a longer period--Say ~950 watts for 20 hours (close enough for our discussion purposes right now).

    Charging wise--you can recharge the bank from the utility power (when it comes back up) in ~10 hours or so. Or, you can use a genset (assume 50% generator loading or higher for best fuel efficiency and 80% charging efficiency):
    • 600 AH * 59 volt charging * 1/0.80 charging eff * 0.05 min charge rate * 1/0.50 generator loading = 4.4 kW minimum genset
    • 600 AH * 59 volt charging * 0.13 max charge rate * 1/0.50 generator loading = 10.8 kW useful maximum genset
    You would have to run the genset, very roughly 8-20 hours to fully recharge your batter bank (based on the above design)...

    If you had other needs (longer battery life, longer power storage), could easily justify making the bank 2x larger or more. However--it still will take more generator runtime to recharge a larger bank (depending on power usage and min/max genset sizing).

    The XW Hybrid inverter can also have solar panels added later for Grid Tied support if you want (and your utility supports some form of net metering).

    $3,000 for the antrex XW4548 120/240-60 Hybrid Inverter-Charger
    $160 Xantrex XW AGS Automatic Generator Start (Xanbus)
    $4,400 for 16x Trojan L16RE-A 325 AH Deep Cycle Battery (6 volt) ~7-10 year life (?)
    $1,140 for a Xantrex XW Power Distribution Panel, Prewired (others less expensive or do it yourself)
    $320 for Xantrex LinkPRO Dual Battery Monitor System (I like Battery Montors)
    $x,000 for wiring, installation, misc. hardware, rewiring new sub-panel for emergency power support, etc.
    $x,000 for backup genset

    The above is a "high end system" (sizing, hardware suggested, supports relatively large loads). You can also build a smaller system with less capability if it better matches your needs...

    Or--just get a small genset (like a Honda eu2000i or eu3000i) and sufficient fuel (2-4 gallons per day or Propane conversion) for emergency power.

    Many folks start with a 8-10kW generator when really a much smaller one can easily supply the emergency loads (I have a grid tied solar system and my backup is a Honda eu2000i and 20 gallons of fuel with stabilizer).

    If you need a slightly larger genset, look at used RV gensets (gasoline, propane, natural gas, diesel). Quiet, electric start.

    A big 7-10kW genset can easily use 1/2-1 gallon per hour of fuel with light loads (less than 50%)... A large genset only makes sense if you have large loads (pumping, electric heating, A/C, etc.).

    Anyway, just taking a "stab in the dark here". ;)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Battery backup power for NW PA

    Thank you for the information ref my plans for back up power source. For now I will try to keep it simple and create a sub panel separated by a one way diode to isolate the essential circuits to provide emergency power. I intend to use a battery back up and an inverter in addition using your suggestion of a small generator to recharge my system when needed. The task in front of me is basic Q and A to determine the electrical load needed and the overall power to be supplied. Thanks again and iIwill most likely be back with more questions. This site is very informative and helpful
    David E.
  • BB.BB. Super Moderators, Administrators Posts: 29,188 admin
    Re: Battery backup power for NW PA
    David E. wrote: »
    For now I will try to keep it simple and create a sub panel separated by a one way diode to isolate the essential circuits to provide emergency power.

    Whoa---I have to go right now... But I am not sure where you are planning to use a blocking diode... There are a few places in DC circuits where it makes sense--but never for AC (use transfer switches).

    Diodes are used to isolate battery banks--but the voltage drop can cause issues with proper battery charging.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • arkieoscararkieoscar Solar Expert Posts: 101 ✭✭✭✭
    Re: Battery backup power for NW PA

    I have put together several small back up systems. An easy way it to use one of the multi circuit transfer switches that are designed for small generators (generac and others make them), an inverter/charger and battery. The ones that I have done were in condos, so no generator was possible and I had to use gel cell batteries. The largest uses a Xantrex Freedom marine 20 and 2/250AH batteries to power the furnace blower, lights, TV, etc. I just finished adding 440 watts of PV to that system to extend it's useful life. It powers a couple of small circuits (computer and one lighting) 24/7.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Battery backup power for NW PA

    David,

    Assuming you're not going to install a PV-based system, the hybrid battery-based back-up system that would work for you would look like the one in the attached drawing.

    Dual battery banks would likely be an unnecessary complication and expense. If the battery state of charge (SOC) were to drop too low during a prolonged outage, the inverter/charger could be switched over from "inverter mode" to "pass-thru / charge mode", and the generator would provide power for downstream backed-up loads and also for recharging the batteries.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Battery backup power for NW PA
    crewzer wrote: »
    David,

    Assuming you're not going to install a PV-based system, the hybrid battery-based back-up system that would work for you would look like the one in the attached drawing.

    Dual battery banks would likely be an unnecessary complication and expense. If the battery state of charge (SOC) were to drop too low during a prolonged outage, the inverter/charger could be switched over from "inverter mode" to "pass-thru / charge mode", and the generator would provide power for downstream backed-up loads and also for recharging the batteries.

    HTH,
    Jim / crewzer

    Jim:
    Thanks for the diagram. One picture is worth a thousand words. Very helpful in starting this project.
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Battery backup power for NW PA

    David,

    :cool:

    Let us know when/how/if we can be of more help!

    Regards,
    Jim / crewzer
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